1. Field of the Invention
This invention relates to a two-way communication medium in the form of double post card or the like for use in communicating, in concealed condition, written information requiring secrecy.
2. Description of Background Art
Hitherto, a double post card of the type which is shown in FIG. 10 has been commercially available as a medium for two-way communication.
Such post card, as generally shown in (a) and (b) of FIG. 10, comprises forward and reply communication sheet portions 1, 2 formed in continuation, the reply sheet portion being adapted to be preprinted with the name and address of an addressee for reply. In this way, the double post card is mainly intended to serve for the convenience of the replier by previously arranging for reducing the expense and trouble which would otherwise be involved on the replier's side. However, as can be seen from (c) and (d) of FIG. 10, such double post card is not intended to keep secrecy of the content of the communication, it being simply folded double without having the sheet portions 1, 2 sticked together by pasting or otherwise when it is initially sent, as well as when it is sent for reply.